The assignee of the present invention has successfully demonstrated apparatus and techniques for online monitoring of rotating and/or stationary components of a turbine engine. See for example, apparatus and techniques described in U.S. Pat. No. 7,690,840 titled “Method and Apparatus For Measuring Online Failure Of Turbine Thermal Barrier Components”, which is herein incorporated by reference in its entirety.
In view of geometrical and thermal constraints that can arise in the context of a confined space access in a turbine engine, the thermal and/or spatial views provided by known apparatuses are generally limited to regions located radially-inward relative to cylindrical structures of the turbine. For example, obtaining thermal and/or spatial views of regions located radially-outward have not been possible or have been substantially limited in both size and/or incident angle.
Additionally, known apparatuses involve relatively long optical paths, which have generally required a relatively large number of optical elements (e.g., relay optics, etc.) since such apparatuses have been located in areas spaced-apart from the high temperatures and/or pressures that generally arise in a path of a working gas of the turbine. A long optical path may force the designer to use optical elements involving optical tradeoffs that may be needed in the context of such a long optical path, such as may involve use of optical elements having relatively low-reflection characteristics. For example, optical elements having relatively high-reflection characteristics may not be suitable in a long optical path involving a large number of such elements but may be suitable in a short optical path involving a lesser number of the optical elements. These considerations may somewhat curtail the ability of the designer to tailor the optical design to address other tradeoffs, such as an ability to use more rugged optical materials, which may have higher-reflection characteristics.
Accordingly, in view of the foregoing considerations, there continues to be a need for improved apparatus and/or techniques useful for monitoring high-temperature regions of interest in a turbine engine.